• 6.5 baseline — 0.6 × season 6.6 (18 gm) + 0.4 × last 10 6.4
• −0.2 opponent leak — they concede 181.6/game vs a 185.9 league average
• +0.0 at this ground — averages 6.5 there (10 gm)
• vs them: averages 7.0 over 4 games — evidence, never summed

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission.